Soon I'm going to be involved in a project that requires me to photograph glass doors in several storefronts. I'm worried about glare and reflections in the glass, and I would appreciate your advice about how to avoid these problems. Would a polarizing filter help? Should I have a large black background behind me that blocks reflections? Should I shoot only on overcast days?
Depending on what's on the other side of that glare it might be easier to just clone stamp repair it in post. Or maybe turn the lights off & on for a couple exposures and blend them. Sometimes shooting with a strong speedlight or two (hidden from reflecting) can control glare...
Thanks for replying. I should have said in my original post that these will be exterior shots. I'll probably be shooting from about 10 to 15 feet from the door and looking at it straight-on. On the other side of the door will probably be a relatively dark store interior. If the sunlight behind me is bright, my camera and I (and cars and pedestrians) will almost undoubtedly be seen in the reflection. Someone suggested to me that I use a large black scrim to block the light, but because it's outdoors, I'll be getting light from any number of directions. You're probably right that I'll end up doing a lot of post-processing.
What's the main subject? If it's the doors themselves, is there really a need to reduce reflections?
If the sun is behind you, that will actually help reduce reflections because everything in the reflection will be in shadow. a CP will definitely help reduce whatever reflections are there. A scrim will help as well, but depending on how far away you are from the door, you'll need a HUGE one, and likely multiple exposures.
Circ. Polarizer is supposed to help with it for sure.
Do you have to photograph during the day? If you can photograph at night with the lights on in the store, the glass will become mostly transparent - only light will appear in the glass. It's much easier to flag a street light or 2 (and wait until there are no cars passing) than try to block everything during the day. You are correct that shooting during the day will require very large amounts of black material as close to the glass as possible. A polarizer will help but will not remove direct reflections.
If you are trying to photograph the door frames themselves, you could bring in strobes that are powerful enough to overpower daylight, use heavy ND filters and an exposure that makes all reflections go dark, then bring in your lights for the frame. You'll probably need studio strobes for enough power so either you have to find power onsite or bring a generator.
Either way - strobes or lots of black material - you are going to have a big presence. That may require a permit, depending on what city you are in.
Good luck-